Back in 1991, Mt Pinatubo erupted in the Philippines. It was an enormous explosion that is estimated to have thrown out 10 billion tonnes of magma and sent ash clouds 34 km up into the atmosphere. It was one of the biggest volcanic eruptions of the 20th century.

Back in 1991, Mt Pinatubo erupted in the Philippines. It was an enormous explosion that is estimated to have thrown out 10 billion tonnes of magma and sent ash clouds 34 km up into the atmosphere. It was one of the biggest volcanic eruptions of the 20th century.

Hundreds of people were killed, thousands evacuated and the ash ejected from the two week eruption drifted right around the world affecting flights and improving sunsets.

The sulphuric fire and brimstone coming from Mt Pinatubo was even enough to affect the world's climate.

In the atmosphere, sulphur dioxide coming from volcanoes forms sulphuric acid - otherwise known as acid rain. This captures the heat from the sun high up in the stratosphere, preventing it from reaching Earth, cooling the Earth's overall temperatures. Scientists estimate that the 15 or so million tonnes of sulphur dioxide spat out by Pinatubo temporarily cooled the globe by as much as 0.5 degrees Celsius.

How then might this latest volcano erupting in Iceland affect the climate? Will it provide the reprieve to global warming the world is looking for?

Sadly no.

Mt Eyjafjallajökull, dramatic though it is, is tiny by comparison.

Dr Andrew Bell, from the School of Geosciences at the University of Edinburgh, says "In both a global and an Icelandic context, this is a relatively minor eruption, involving only small amounts of magma."

The sulphuric emissions from Eyjafjallajökull are accordingly small. Steve Sparks, director of the Bristol Environmental Risk Research Centre at the University of Bristol, says "the reported sulphur dioxide fluxes have been about 3,000 tons per day."

Even if the eruption has released this much daily for a month, this equates to only about 90,000 tonnes of sulphur dioxide.

Australian industry emitted 2.7 million tonnes of sulphur dioxide in 2008/2009, or more than 7,000 tonnes per day.

A rain of ash

Ash also has the ability to obscure the sun, leading to cooler days. Dr Blair Trewin of the National Climate Centre in Melbourne says in its current form the ash cloud is unlikely to have the same impact on global temperatures.

"For a volcano to have a significant global cooling effect it has to get its ash up into the stratosphere," he says. "If it doesn't, the ash will get rained out fairly quickly." ABC Science has the story here.

Carbon dioxide

Volcanoes also emit carbon dioxide in the toxic mix of gases that are released in an eruption. Carbon dioxide is one of the gases that cause climate change.

Last year Ian Plimer asserted that the carbon dioxide coming from all the world's volcanoes was one of the major contributing factors to changes in atmospheric CO2.

"Over the past 250 years, humans have added just one part of CO2 in 10,000 to the atmosphere. One volcanic cough can do this in a day," he said.

Could Eyjafjallajökull's rumblings, or indeed Pinatubo's, exacerbate climate change, rather than mitigate it?

Pinatubo is estimated to have belched 42 million tonnes of CO2 into the atmosphere in 1991. Globally, according to the US Energy Information Administration, human activity contributed 29,195 million tonnes of CO2 to the air in 2006 - nearly 700 times as much as Pinatubo's colossal cough.

While Pinatubo was undoubtedly a big contributor to global CO2 levels in 1991, these figures contradict Plimer's view of the relative importance of volcanic activity on the Earth's carbon dioxide levels.

So overall, while Eyjafjallajökull might be coughing out all kinds of underground gases, the largest effect it will have on the world will be keeping planes on the ground. It is unlikely to have any lasting effect on our climate.

As Steven Sherwood, professor of physical meteorology and atmospheric climate dynamics at the Climate Change Research Centre, University of New South Wales said, "Satellite images show that the plume is not thick or expansive enough to significantly affect climate, though it could produce slightly cooler days in places where it lingers over one spot for the whole day, I'm not sure anyone would notice the effect."

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Comments (43)

g w :

06 May 2010 11:44:28am

If e =mc2 then we are seeing the earth gain in size every day as plants convert the suns rays ito matter. Thus causing the earth to gain mass and the core to heat more. It is not hard to think that the tranfer of energy to matter has a by product of heat as the atoms are changed

Rare Educated American :

11 May 2010 11:00:38am

Actually E=mc^2 is the equation relating the mass of an atom to the energy contained within the atom. Plants do not create mass through the process of photosynthesis, they simply are harnessing the energy from the sun to combine simple molecules into complex molecules. When this process occurs, the mass and energy are conserved, however, the energy is stored as potential energy in molecular bonds in the complex molecules. Since heat is a form or energy, there is actually a net decrease in energy. Furthermore, the core of the earth is actually cooling despite what climatologists predicting global warming would lead you to believe. This is due to the second law of thermodynamics which states that the entropy (or energy) of an isolated system will increase unless it is in balance with its surroundings. While considering only the system of the sun and the earth, you would be correct in assuming that the earth is increasing in temperature. However the fact that the earth is part of the larger system, namely the universe, which is as a whole cooler on average than the earth, the earth must be losing energy (heat). Global warming is simply a heating of the outer layer of the earth. Another way of thinking of it is that global warming is simply slowing down the loss of heat from the core, with the atmosphere acting as a sort of blanket containing the heat.

Matt Andrews :

19 Apr 2010 12:16:52pm

A reasonable summary article, spoiled by the bizarre use of a Plimer quote (on CO2 from volcanoes) as if it were remotely factually based. See http://www.skepticalscience.com/volcanoes-and-global-warming.htm for one of many rebuttals of Plimer's ridiculous statement.

The ABC needs to learn to stop treating climate denialists as if they are credible sources, and start treating them according to the level of scientific support for their positions, which is pretty much in line with the HIV-denialists and other fruitloops. Just because News Ltd and assorted right wing politicians give them a platform does not mean they have scientific credibility.

ardy :

20 Apr 2010 11:46:20am

Matt Andrews: If Plimer is wrong then he at least made a statement that is provable or refutable by observation not some pie in the sky computer model based on lousy code, very dirty and poorly handled data.

Glenn :

22 Apr 2010 11:12:10am

If Plimer is wrong!? He stated that "Over the past 250 years, humans have added just one part of CO2 in 10,000 to the atmosphere. One volcanic cough can do this in a day." One part per 10,000 is 100 parts per million. Plimer therefore agrees with climate scientists that human activity substantially has caused the increase from about 280 ppm worldwide at the start of the Industrial Age to around 380 ppm now. To claim that the worldwide CO2 content could increase by 100 ppm in a single day, for any reason, is facile.

John :

19 Apr 2010 11:09:26am

Keep in mind the size of the region currently impacted by volcanic ash. I believe it is less than the areas that had a very cold (northern) winter. Despite that cold weather global average temperatures increases, as one would expect with El Nino conditions.

I'm fairly certain that unless there's a big increase in the size of the volcanic cloud it is very unlikely that there will be a discernible influence on global temperatures.

Be aware though that this won't stop some people making all kinds of claims on the basis of the output of models. They'll be busy saying things like "The world cooled by X", teh flip side of which is "The world would have warmed by X if not for the volcano."

Merry Widow :

19 Apr 2010 10:26:56am

Svante Arrhenius, (1859-1927) physicist and chemist, was famous for discovering CO2's warming abilities and the GHG effects and there remains a universal consensus. Scientists, some years ago, estimated that humans emit about 130 times more CO2 than volcanoes. Australia's ignominious C02 emissions means it's coming dead last in the OECD countries. Fraudsters and big oil and coal sycophants,Plimer, Monckton et al, should be placed under detention for "crimes against humanity."

cop15 :

Anon :

19 Apr 2010 6:29:24am

Steve Sparks seems to be neglecting one fairly significant detail though - that while the overall output of sulphur from this Icelandic volcano may pale in comparison to anthropogenic pollution; our output takes some time to travel several kilometres into the atmosphere, while the volcano injects it directly to heights where it can do its worst (or best, I guess).

hunter :

19 Apr 2010 1:06:09am

3000 tons of SO2 per day in such a lively eruption seems very low. With so much of the article intent on deconstruction of Pilmer, I think it best to wait and see the real numbers before accepting much of the alleged facts of this article.

faither ®:

18 Apr 2010 7:38:41pm

Folks in UK are saying the sky has never looked so blue, not a contrail in sight. The lack of contrails will allow more sunlight in, raising temperature slightly. This effect has now been retrospectively added to current computer models. The net result will lead to a dramatic increase in warming. With luck displaced Icelanders will be able to re-inhabit Greenland. ;-)

james :

18 Apr 2010 4:50:22pm

Where does this new eruption, (not to mention all the other ones taking place beneath the waves,) leave all the silly models put out to the year 2100. You wouldn't know what was going to happen, no one does you arrogant bloody asses.

Douglas McClean :

21 Apr 2010 12:55:37pm

It leaves those predictions about where my latest fart leaves the predictions for tomorrow's weather: right where they were. This is a small eruption, of the kind that happens all the damn time, and would be of no consequence to anyone if it weren't for vagaries of timing, winds, and the local geology that makes it an ash-heavy eruption. This kind of stuff is tiny tiny tiny noise on top of the large and robustly attributed AGW signal.

vickiii :

18 Apr 2010 4:17:51pm

I love the way they say that CO2 is a climate warming gas. This is yet to be shown. From most of the research in this area it would seem clear that the earths temperature is very closely related to sunspot activity. Wow amazing that - the sun effect our climate??!

VinceOZ :

bulldust :

17 Apr 2010 10:14:27am

But think of all the flights that were grounded... all the man-made CO2 emissions averted. This is what the politicians and AGW-advocates are seeking to achieve indirectly with their ETS policies. Don't tell me all those grounded flights sre not helping to save the planet! Then all the ETS taxation policies would be for naught... nooooo*

m1scha_m :

17 Apr 2010 7:35:24am

What... no comments; although I would imagine the 'human race aint done nothing' brigade won't want to post as it does nothing for their case. They will just get Alan Jones to ask Plimer to contradict all the scientific evidence on the basis of a few old misrepresented emails taken well out of context.

Stuart :

18 Apr 2010 5:06:56pm

I am a ignorant global warming sceptic so you will hate me and ignore what I say but I am new to this blog and confused You keep rubbishing Professor Plimer who ever he is. If we are going to rubbish people please can people list any relevant qualifications they have at the end of their post not degrees in law or stamp collecting but physics, Meteorology etc. then we may get some kind of real debate going from people who know what they are talking about not a load of ignorant brain washed people.

Robert Stewart :

17 Apr 2010 5:58:04am

An interesting comment Sarah but you selectively give a quantity of CO2 from human source without adding the reality of bushfires. The tonnage of CO2 discharged into the atmosphere in as many hours that has taken the vegetation so many years to absorb in tyhe process of providing the oxygen for life itself. It is worth considering that the relentless loss of vegetation is responsible in addition to direct human causes. The balance is lost and will be more so as an extra 2 billion souls over the next 40 years will breathe the oxygen from the moment they are born. Will that come from an emissions tax on the human causes.

Markus :

Anon :

17 Apr 2010 5:38:51am

Yes, at the moment it is a small eruption, the problem being if it trigers its bigger neighbour the Katla volcano. Have a look at the Laki Fissure to see what Icelandic volcanoes are capable of- def able to change the climate.

David Sentinella :

17 Apr 2010 4:24:13am

Ian Plimer's comment is completely wrong and deliberately misleading.

When he states, "Over the past 250 years, humans have added just one part of CO2 in 10,000 to the atmosphere.", he is diminishing the rise from about 280 ppm, the pre-industrial level, to 387 ppm, the current level, probably better stated as nearly a 40% increase.

It is a complete lie for Plimer to say “One volcanic cough can do this in a day.” This would equate to about 520 Gt (Giga-tonnes). Pinatubo’s 42 Mt (Mega-tonnes) was 12,000 times less than that.

The article is correct to identify that, “these figures contradict Plimer's view of the relative importance of volcanic activity on the Earth's carbon dioxide levels.”, however it’s more than a contradiction, it’s a gross distortion and a complete lie. How can he call a volcanic event 12,000 times greater than Pinatubo, “a cough”?

Fran Barlow :

19 Apr 2010 12:02:03pm

You are quite right David though you understate. While it is certainly the case that atmospheric Co2 has increased by 40% over the longterm pre-industrial level, this figure would be a lot higher, but for the substantial ocean and terrestrial sinks we have. Massive land clearing by the US as they colonised the American land mass meant that as vegetation recovered, Co2 was reabsorbed.

So the total impact of inustrial emissions is masked by our sinks. It is important to realise, much as sweeping rubbish under the carpet is not sustainable, but may give the superifcial appearance of a household producing less waste than one that leaves its rubbish where it lands, the output would be the same.

Total emissions to the biosphere are far greater than the rise in atmospheric inventories suggests.

HH :

16 Apr 2010 8:59:44pm

" humans have added just one part of CO2 in 10,000 to the atmosphere" -- too bad they have not mentioned that this fact can result in catastrophic climate changes if this amount of emissions will be maintained!

DP :

16 Apr 2010 8:56:38pm

Sarah, I hope nobody, my former colleague Ian Plimer included, would consider that the Iceland volcano's recent unexpected eruption will alter the very nature of climate variability as presently set. Furthermore, you miss the point completely about volcanoes and their contribution to CO2 levels and climate dynamics more generally. Eruptions are occurring all the time, mostly in the ocean and particulrly in its trenches. It is the SUM of these ongoing eruptions, now given a boost bigger than any SUV can muster, that Plimer and other geologists relate to climate - not, for "heaven + earth's" sake, one eruption as you mischievously imply.

David Arthur :

What's particularly useful is the comparisons between magnitudes of volcanic, and anthropogenic, contributions of carbon dioxide and sulphuric oxides to the atmosphere.

What's also useful is the comparisons between statements made by Ian Plimer, and reality. That said, has Professor Plimer been afforded the opportunity to review his past statements in the light of aforementioned comparisons?

Shalashaska :

John Quiggin :

16 Apr 2010 4:24:07pm

Plimer's claim has repeatedly been shown to be false, as indeed do the EIA estimates cited immediately afterwards. You really need to spell this out, rather than relying on readers to work out that Plimer is full of it.

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About the Editor

Sara Phillips

Sara Phillips has been an environment journalist and editor for eleven years. Learning the trade on environmental trade publications, she went on to be deputy editor of 'Cosmos' magazine and editor of 'G', a green lifestyle magazine. She has won several awards for her work including the 2006 Reuters/IUCN award for excellence in environmental reporting and the 2008 Bell Award for editor of the year.

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